CV-Bowen opened a new pull request, #17761:
URL: https://github.com/apache/nuttx/pull/17761
## Summary
This PR series addresses critical issues in the rpmsg/openamp subsystem
related to mutex handling and service lifecycle management.
## Changes
### 1 openamp/libmetal: Change mutex to recursive mutex to prevent deadlock
Changed libmetal mutex implementation from regular mutex to recursive mutex
(rmutex) to prevent crashes when locks are acquired twice in nested scenarios.
Problem: During the destroy process, we hold rdev->lock while iterating
rdev->endpoints to destroy all endpoints. However, rpmsg_destroy_ept() may send
a name service message, which attempts to acquire rdev->lock again, leading to
a deadlock and crash.
Solution: Use recursive mutex in libmetal to allow the same thread to
acquire the lock multiple times safely.
### 2 drivers/rpmsg: Remove held status check after rmutex change
Since metal_mutex has been changed to rmutex_t, removed the redundant held
status checks in rpmsg drivers (rpmsg_port.c, rpmsg_virtio_lite.c, rptun.c).
The recursive mutex naturally handles re-acquisition scenarios.
### 3. rpmsg: Call unbound_cb for server/client services during destruction
Problem: Before this patch, rpmsg services were not properly destroyed after
calling rpmsg_device_destroy(). This caused errors when calling
rpmsg_device_created() during a second connection attempt with the peer.
Solution: Properly invoke unbound_cb callback for services used as
server/client during the destruction process to ensure complete cleanup.
## Impact
Rpmsg and Rptun
## Testing
cmake -B cmake_out/v8a_server -DBOARD_CONFIG=qemu-armv8a:rpserver_ivshmem
-GNinja
cmake --build cmake_out/v8a_server
cmake -B cmake_out/v8a_proxy -DBOARD_CONFIG=qemu-armv8a:rpproxy_ivshmem
-GNinja
cmake --build cmake_out/v8a_proxy
qemu-system-aarch64 -cpu cortex-a53 -nographic \
-machine virt,virtualization=on,gic-version=3 \
-chardev stdio,id=con,mux=on -serial chardev:con \
-object
memory-backend-file,discard-data=on,id=shmmem-shmem0,mem-path=/dev/shm/my_shmem0,size=4194304,share=yes
\
-device ivshmem-plain,id=shmem0,memdev=shmmem-shmem0,addr=0xb \
-mon chardev=con,mode=readline -kernel ./nuttx/cmake_out/v8a_server/nuttx \
-gdb tcp::7775
qemu-system-aarch64 -cpu cortex-a53 -nographic \
-machine virt,virtualization=on,gic-version=3 \
-chardev stdio,id=con,mux=on -serial chardev:con \
-object
memory-backend-file,discard-data=on,id=shmmem-shmem0,mem-path=/dev/shm/my_shmem0,size=4194304,share=yes
\
-device ivshmem-plain,id=shmem0,memdev=shmmem-shmem0,addr=0xb \
-mon chardev=con,mode=readline -kernel ./nuttx/cmake_out/v8a_proxy/nuttx \
-gdb tcp::7776
server log:
```c
NuttShell (NSH) NuttX-12.10.0
server>
server>
server> rptun ping all 1 1 1 1
[ 0.000000] [ 5] [ EMERG] [server] ping times: 1
[ 0.000000] [ 5] [ EMERG] [server] buffer_len: 2032, send_len: 17
[ 0.000000] [ 5] [ EMERG] [server] avg: 0 s, 18603232 ns
[ 0.000000] [ 5] [ EMERG] [server] min: 0 s, 18603232 ns
[ 0.000000] [ 5] [ EMERG] [server] max: 0 s, 18603232 ns
[ 0.000000] [ 5] [ EMERG] [server] rate: 0.007310 Mbits/sec
server>
server>
server> ps
PID GROUP PRI POLICY TYPE NPX STATE EVENT SIGMASK
STACK USED FILLED COMMAND
0 0 0 FIFO Kthread - Ready 0000000000000000
0008160 0001792 21.9% Idle_Task
1 0 192 FIFO Kthread - Waiting Semaphore 0000000000000000
0008096 0001344 16.6% hpwork 0x4046dc08 0x4046dc88
2 0 100 FIFO Kthread - Waiting Semaphore 0000000000000000
0008096 0001344 16.6% lpwork 0x4046dcb8 0x4046dd38
4 0 224 FIFO Kthread - Waiting Semaphore 0000000000000000
0008096 0001776 21.9% rptun proxy 0x40488550
5 5 100 FIFO Task - Running 0000000000000000
0008128 0004240 52.1% nsh_main
server>
server> rptun dump all
[ 0.000000] [ 5] [ EMERG] [server] Remote: proxy headrx 8
[ 0.000000] [ 5] [ EMERG] [server] Dump rpmsg info between cpu (master:
yes)server <==> proxy:
[ 0.000000] [ 5] [ EMERG] [server] rpmsg vq RX:
[ 0.000000] [ 5] [ EMERG] [server] rpmsg vq TX:
[ 0.000000] [ 5] [ EMERG] [server] rpmsg ept list:
[ 0.000000] [ 5] [ EMERG] [server] ept NS
[ 0.000000] [ 5] [ EMERG] [server] ept rpmsg-sensor
[ 0.000000] [ 5] [ EMERG] [server] ept rpmsg-ping
[ 0.000000] [ 5] [ EMERG] [server] ept rpmsg-syslog
[ 0.000000] [ 5] [ EMERG] [server] rpmsg buffer list:
[ 0.000000] [ 5] [ EMERG] [server] RX buffer, total 8, pending 0
[ 0.000000] [ 5] [ EMERG] [server] TX buffer, total 8, pending 0
server> uname -a
NuttX server 12.10.0 0cb3aa6c84 Jan 4 2026 15:10:56 arm64 qemu-armv8a
server>
```
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